Hi, motivated by your earlier comparison between 2.2.15 and 2.2.16 andthe possibility that the new elevator might be causing the slowdown idid some benchmarks of my own.

My conclusion is that the new elevator isnt causing a slowdown, but itneeds to be tuned.

The results for my raid0 array shows that 2.2.16 is a few % slower than2.2.15, but maybe that could be overcome with more experimentation withelvtune.

The tiobench option *--nofrag* made a lot of difference as the number ofthreads increased, without --nofrag the performance drops off a lotfaster, if you didnt use it on your tests i would be interested to seeif you have the same experience.

/mnt1 is a Quantum Fireball Plus KA18.2/mnt2 is a Quantum Fireball Plus KX20.5/mnt3 and /mnt4 are both IBM-DPTA-372050

All are on there own channel in udma66 mode via two Promise PDC20262cards.The machine is a dual 433 celeron with 64MB ram

Both 2.2.15 and 2.2.16 have the latest ide and raid patches applied.For 2.2.16 i settled on using elvtune -r 100000000 -w 100000000 -b 128.I experimented with a few different elevator values, it seems that bydecreasing -b on the elevator the speed of a single thread increases,but the speed degrades faster as the number of threads increases.Anyone have good knowledge on tuning the elevator ?

As can be seen from these results there is no slowdown as threadsincrease using the --nofrag option.

I used the same partitions on the same drives as tested above and putthem in a 4 way raid0 with a chunk size of 16K, i also added --blocksize16384 to tiobench.pl to test with the same blocksize and chunk size.